Synchronizing system



. c. F. JENKINS March 28, 1933. SYNCHRONIZING SYSTEM Re. 18,783

, 5 Sheets-Sheet 1 Original Filed July 21, 1927 C. F. JENK INS I March 28, 1933- SYNCHRONIZING SYSTEM 18,783

5 Sheets-Sheet 2 Original Filea July 21, 1927 c. F. JENKINS 7 March 28, 1933. SYNCHRONIZING SYSTEM Ri 8,783

3 Sheets-Sheet 3 Original Filed July 21, 1927 AAAA Shucntob u vention.

mama. Mar. 28, 1933 UNITED STATES PATENT "OFFICE" cEAnLns rmcls mums, or wasnnmron, msrnrc'r or 'commnm, Assxouoa To 1 mums mommoams, me. or smvma. srame, A coarona'rion'or TEE DISTRICT OF COLUMBIA SYNOHBONiZING srs'rrm I ori am llo. anaaujda a... 24, 1930, Serial No. 207,515, filed July 21, 1927. Application for reissue fled rare-11.22, 19 2. Serial in. 000,549.

This invention relates to picture transmission systems, and in particular to arrangements for maintaining synchronous operation between the transmitting apparatus at the transmitting station and the receiving apparatus at the receiving station.

An object of my invention is to provide means for automatically maintaining a definite speed relationship between the transmitting and receiving apparatus. i

Another object of my invention is to devise novel relay apparatus capable of responding to electric current variations of relatively high frequency.

- My invention is illustrated in the accompanying drawings in which like reference characters represent like parts.

Fi e 1 is a diagrammatic showing of one orm of my invention employed at the receiving station.

Figure 2 is a diagrammatic representation of 'a second formof apparatus employed at the receiving station.

Figure 3 is a third modification of the In Figure 1, a motor 11 is arranged/ ito drive a cylindrical drnm- C upon which is mounted the surface or film which is to re- Y "ceive the picture being transmitted. The 19 motor M- com rises an armature A and a field winding each of which is supplied with current from the battery B. The armature circuit of the motor is completed from battery B through the output circuit of amglifier A3, armature A, and back to battery The armature also hasa shunt circuit from battery B through resistance R1- The receiving station is provided with a radio receiving set comprising a detector D1 40 and an amplifier A1. Connected to the output circuit of amplifier A1 is a second amplifier'A2, the output circuit of which 'contains an incandescent lamp L. The picture recording. apparatus is alsoconnected to thet6 output circuit of amplifier A1 and comprises,

for example, a solenoid S arranged to operate an inkin pen P. A lens L1 is arranged togather t e divergent rays proceeding from lamp L and focus them-upon a lightsensitive cell LS connected in the input cirher. 4, 1928. ceived at the receiving station and detected cuit of amplifier A3. A disc D, provided witha series of holes arranged around its periphery, ismounted upon the shaft of motor A andis arranged to rotate in the path sensitive cell S by the lens L1. The width of the openings in disc D is preferably equal of the rays of light projected upon lighta to half the distance between the openings,

although thisratio may be varied considerabl if desired. V

he operation of Figure l is as follows It is to be understood that a radio wave is .being transmitted from the transmitting bear a definite relation to the speed of the transmitting apparatus and may be produced in any desired manner, but I prefer to employ a light-chopper for this purpose, as disclosed in my United StatesPatent No. 1,694,065, granted to C. F. Jenkins, Decem- The modulated wave is reby detector D1 to'derive therefrom low fre quency currents which represent both the picture light variations and the synchroniz- U ing impulses. This composite current is supplied to-amplifier A1 where it is amp11 ed and supplied to the. output circuit.

The amplified current is supplled to the recording apparatus which responds to the picture variations and causes the pen P to record upon the picture receiving surface, mounted upon drum C, ink marks corresponding to the dark portions of the picture being transmitted. The recording apparatus need not necessarily respond to the synchronizing interruptions or variations. A portion of the current in the output circuit.

of amplifier A1 is supplied to the input circuit of amplifier A2, and lamp L1 is caused to vary in intensity in accordance with the current variations. Accordingly, the beam of light falling upon the lightsensitive cell S will vary in intensity in accordance with the synchronizing yaria lm tions. The of light is also subject to controlby disc D in the following man- 'ner: In case the motor M is rotating at and the phase relation of the disc with re-' spect to the synchronizing impulses is such that each pulse reaches a maximum as a hole in disc D is centered with respect to the beam of light, the effect of. the beam of light upon the light-sensitive cell LS will be a maximum. 'It will thus be seen that light-sensitive cell LS will be inter mittently illuminated at a frequency equal to that of the synchronizing variations. The light-sensitive cell will cause amplifier A3 to produce corresponding current variations in the armature circuit of motor M. In case disc D has such phase relation that a synchronizing pulse reaches its maximum when a solid portion of disc D is passing in front of the light ray,the efiect of the ray upon light-sensitive cell LS will be a mlmmum, and the current variations produced in the armature circuit of motor M will be very small. For intermediate phase relations of the holes in disc D with respect to the synchronizing pulses, the eifect of the light rays upon the light-sensitive cell will be to produce intermediate values of current variation in the armature circuit. The speed of motor M is adjusted by resistance R1 to such value that it is slightly below .thedesired synchronous speed; The effect ofthe current ulses produced by the light-sensitive cell Lg in the armature circuit is to increase the motor speed. Ac-

f cordingly, disc D will assume such phase relation with respect to the synchronizing pulses or variations of lamp L that the amplitude of the current pulses produced by S is just suflicient to maintain the motor in synchronous operation with the incoming synchronizing pulses. In case the load u n the motor is increased for any reason, disc D will lag behind the synchronizing pulses by an amount. suflicient to increase the am litude of the current roduced 8y light-sensitive cell and to therebysup 1y to the armature A, increased current clent to accommodate the increased, load: Conversely, if the load is decreased from its normal value, the motor will momentarily speed up and cause disc D to advance in phase relation withrespect 'to the synchronizin variations, and the resul current rodu'ced by lightsensitive cell L will correspondingly reduced, and the motor will be prevented fromgetting'out of sy'nchronism. Y

The arrangement shown in Figure 2 the same as that shown in Figure 1, except for the details of the motor control arrangement. In this figure, as inFigure 1, both the armature and the field of the motor are supplied with current from battery B. The armature circuit of the motor also includes an adjustable resistance R1. In a shunt path around resistance R1, a rotating commutator CM mounted upon the shaft of the motor is connected in series with contacts GT-CP of a special electric relay. The relay comprises a glass tube MF provided with an electrode E mounted in each vend thereof. The tube is filled with an acidulated solution and also contains a globule of mercury GM immersed withinthe solution. The insulated contacts GTCP are mounted upon the tube and extend into the solution and normally contact with "the globule of mercury as shown in the figure. Electrodes E-E are connected to the output circuit of amplifier A1, and contact points GT-CP are connected in series with commutator CM in a shunt circuit around resistance R1 in the armature circuit.

The operation of Figure 2 is as follows: 7

The speed of motor sistance R1 until it is slightly lower than the desired synchronous speed. With contacts is adjusted by re- I GTCP bridged by mercury GM, resistance dependent upon the conjoint actionof the. a

. commutator CM and the relay, and the time of short-circuit of resistance R1 is dependent upon the phase relationship existing between the commutator and the relay. If the commutator and the relay operate simultaneously to close their respective contacts, re-

sistance R1 will be effectively cut out of the armature circuit for a maximum period. If the commutator and relay become displaced in phase in their operation the period of short-circuit will be reduced and resistance R1 will'have greater effect in limiting the speed of motor M. Accordin ly, with a given load upon the motor an with a given adjustment of the circuits, the motor M will automatically adjust commutator GM to such phase relation with respect to the relay operation that the efl'ectiveness of re,-

sistance R1 in the armature circuit is just suflicient to maintain the motor atsynchronous s crease for any reason, the commutator CM If the load upon the motor'is iny mp3s , such position that resistance R1 is effectively *short-circuited for a period of time suflicient r to increase the armature current by an 3 amount necessary to compensate for the increased load. Conversely, if the load upon the motor is decreased, the commutator CM tends to advance in phase relation with respect to the operation of the relay and there-- by "decrease the period of short-circuit of resistance R1 which will offset the tendency of the motor to increase in speed above synchronous speed.

The arrangement shown in Figure 3 is the same as that shown in Figure 2, except for the details of the relay. The relay shown in Figure 3 comprises a contact arm CA pivoted ata point (a). Cooperating with the contact arm is a stationary contact plate CP. The arm CA is normally held out of contact with plate CP by means of a wire W, one end of which is attached to the arm and -the other end is anchored to a fixed terminal (b). A spring S1 is attached to the arm CA and tends to cause the arm to contact with plate GP. Wire W is connected to the output circuit of am lifier A1, and contact arm CA and plate C are connected in series with commutator CM .in a

. shunt path around resistance R1. Wire W .is made of such material and such diameter that it is readily heated by current supplied from amplifier A1. The efiect of the pulsating current flowing in wire W is to cause the wire to become elongated periodically and in synchronism with the synchronizing impulses. Spring S1 causes the arm CA to contact with plate GP each time wire W is elongated by the amplified current. Thus, the relay contacts willhe closed periodically and in synchronism with the'synchron'izing signals. The action of the arrangement shown in Figure 3 willbe-readily understood from the foregoing explanation of the operation of Figure 2.

It is apparent that the arrangements sho in Figures 2 and 3 will also operate with recording apparatus.

The circuits of the relays have very little inductance and offer smallimpedance to high frequency currents.

It is to be noted that in Figure 1, I em-' ploy a form of electric relay having no moving mechanical parts, and the motor control system does not employ vibrating or sliding electric contact devices. a v

What I claim is- 1. In a synchronizing system the combination of means for producing synchronizing current variations, a motor to be synchronized, a source of current for operating said motor, means for translating said current into corresponding light variations, means to translate said light variations into current variations in the motor circuit, and means controlled by the motor to vary the effect of said light variations upon the cur rent in the motor circuit.

2. In a synchronizing system the combination of means for producing synchronizing current variations, a motor to be synchronized, a source of current for operating said motor, means for translating saidcurrent into correspondin light variations, means to translate said light variations into current variations in the motor circuit, means. controlled in accordance with the speed 01 the motor for varying the effect of said light variationsupon the current in the motor circuit.

3. In a synchronizing system the' combination of means for producing synchronizing current'variations, a motor to he s nchronized, a source of current for operating said motor, means for translating said current into correspondin light variations, means to translate said light variations into current variations in the motor I circuit, means for controllin the effect of said light variations inaccor ance with the relative phase displacement between the angular rotation of the motor and the synchronizing variations. 7

4. The method of synchronizing the operation of a motor which consists 1n contlnuously transmitting from a sending station synchronizing current impulses, translating the said impulses into corresponding light variations, controlling the current supplied to the motor in'accordance with the light ins variations, and varying the effect of the g light variations in accordance with the speed 0 the motor.

5. The method of synchronizingthe oper ation of a motor which consists in continuously transmitting from a sending station synchronizing current impulses, translating the said impulses into corresponding light variations, controlling the current supplied to the motor in accordance with the light variations, and varying the effect of the light variations in accordance with the rela-- tive nhase displacement between the angunizing impulses.

lar rotation of the motor and the synchro- 6. In a synchronizing system the combination of means for producing synchronizing current variations, a motor to be synchronized, a source of current for operating said motor, an incandescent lamp controlled by the synchronizing current, a light-sensitive cell controlled by light from said lamp and connected-to supply current variations to said motor circuit, and a light-interrupting disc driven by the motor and arranged between the lamp and light cell.

-7. l An electric relay system comprising means for translating current variations ins to corresponding light variations, means for translating said light-variations into current variations, and means controlled by said current variations for controlling the action of the light upon the light translating means.

8. In a synchronizing system the combination of means for producing synchronizing current variations, a motor to be synchronized, a periodic circuit interrupter operated by said motor, a second circuit interrupter aving an operating circuit of substantially no inductance connected to 'the source of synchronizing current, and circuit connections whereby the operation of the motor is controlled by the conjoint action of said interrupters. I

9. The method of limiting-the phase displacement of a local motor such as used in radiographic receiving apparatus and which is to run within givenlimits of phase and syn- 1s,7es I ing said varied signals control the e of the local motor.

11. The method of synchronizing radiographic apparatus, which comprises producing at the transmitting station a continuous series of electrical signals of redetermined duration, indeterminate or er and of astrength variable in accordancewith areasexisting between the apparatus in the two stasynchronizing.

12. The method of limiting the phase displacement of a local motor such as used in radiographic receiving apparatus and which is to run within given limits of phase and synchronism with respect to a distant motor, which consists in producing a great plurality of successive high-frequency signals, each of a duration which is a function of the speed of the distant motor and of the shade characteristics of a vispal representation to'be transmitted, varying the instantaneous strength of the signals responsive to simultaneous phase difference of the motors, and applying energy controlled by the varied signals to afl'ect the speed of the local-motor.

In testimony whereof I have hereunto set tions; and applying the varied current for my hand on this 18 day of March, 1932.

chronism with respect to a distant motor,

which consists in produc' a great plurality of successive high-frequency als each of a duration which is a function vo the speed of the distant motor and of a stre h-which varies in accordance with an area 0 an image to be transmitted, applying said signals to control the speed of the local motor, and varying the strength of each signal to afiect the speed of the local motor in accordance with simultaneous phase difference existing between the motors.

10. The method of limiting the phase dis placement, at a local station, of a local motor such as used in radiographic receiving apparatus and which is to run closely in syn chronisnrwith respect to a distant motor at a distant station; which consists in producing at the distant station a great plurality of successive high-frequency signals in de-' terminate order and of a duration which is -ferences existing between the motors; and

continuously and at high-frequency apply- 

